1 research outputs found
HuR biological function involves RRM3-mediated dimerization and RNA binding by all three RRMs
HuR/ELAVL1 is an RNA-binding protein involved in
differentiation and stress response that acts primarily
by stabilizing messenger RNA (mRNA) targets.
HuR comprises three RNA recognition motifs (RRMs)
where the structure and RNA binding of RRM3 and
of full-length HuR remain poorly understood. Here,
we report crystal structures of RRM3 free and bound
to cognate RNAs. Our structural, NMR and biochemical
data show that RRM3 mediates canonical RNA
interactions and reveal molecular details of a dimerization
interface localized on the -helical face of
RRM3. NMR and SAXS analyses indicate that the
three RRMs in full-length HuR are flexibly connected
in the absence of RNA, while they adopt a more compact
arrangement when bound to RNA. Based on
these data and crystal structures of tandem RRM1,2-
RNA and our RRM3-RNA complexes, we present a
structural model of RNA recognition involving all
three RRM domains of full-length HuR. Mutational
analysis demonstrates that RRM3 dimerization and
RNA binding is required for functional activity of fulllength
HuR in vitro and to regulate target mRNAs
levels in human cells, thus providing a fine-tuning
for HuR activity in vivo.Peer reviewe